Rumen

(Science: zoology) The first four stomachcompartments in ruminantanimals (such as cattle and deer).
The first compartment of the stomach of a ruminant; here food is collected and returned to the mouth as cud for chewing.An area of the oesophagus in ruminant organisms where the 'cud' is stored to be regurgitated later and broken down. The rumen hosts a large volume of bacteria which can break down the cellulose of the cell walls in the digested material.